Various optical systems are required to operate in adverse environments, in which various solid particles and/or fluid droplets etc. and/or other agglomerations of one or more materials of various stickiness or viscosity (herebelow collectively termed “debris”) may adhere to the lens and reduce image quality.
One solution is a centrifugal lens protector, in which a spinning glass disc is placed before the lens, so that all the particles are intercepted by the disc. The centrifugal force generated by the disc as it rotates throws the particles towards the circumference of the disc, where they fall off and/or otherwise stop interfering with the image.
U.S. Pat. No. 5,223,880 to Rapp, the disclosure of which is incorporated herein by reference, describes a camera protector in which the disc is integrated with a rotor of a magnetic motor, with a casing surrounding the disc being the motor housing.
U.S. Pat. No. 5,315,333 to Nash, the disclosure of which is incorporated herein by reference, provides a single motor coupled to the disc using a band. The disc is mounted on two lines of bearings. The lens protection device is mounted on the camera, to isolate lens from gyroscopic and vibration forces.
Australian application 9515074, the disclosure of which is incorporated herein by reference, describes another band-based system, in which the disc is said to rotate at between 2600 and 3000 RPM. It is suggested to use a curved or hydrophobic surface to assist in water removal. The motor can be powered using the camera battery pack or using a separate battery.
A particularly difficult environment to view is the inside of the human body. Various medical instruments have been devised for this purpose, for example: the endoscope, the laparoscope which is used for treatment, for example surgery or cauterization or alternative methods of treatment. Commonly an endoscope lens becomes at least partially occluded by body fluids and particles, becoming inoperative. In such circumstance the lens must cleaned. One method of cleaning the lens is to stream a jet of water at the lens, the stream coming from a tube which generally is an integral part of the endoscope assembly. Sometimes the endoscope must be withdrawn for cleaning and reinserted, a time-consuming, risk-increasing and often uncomfortable procedure.